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Stromboli and Mount Semeru Erupt on Same Day, a Week After Mauna Loa

Story by Robyn White • 

Two volcanoes, Italy's Stromboli and Mount Semeru in Indonesia, erupted on the same day, a week after Mauna Loa in Hawaii.


These photos show past volcanic eruptions at Italy's Stromboli, left, and Mount Semeru in Indonesia. The two volcanoes are currently erupting at the same time.

© Getty Images/AZ68/ JUNI KRISWANTO

Mount Semeru, which lies 400 miles southeast of Indonesia's capital, Jakarta, began erupting Sunday at 2:46 a.m. (2:46 p.m. ET). Volcanic ash has rained down on nearby communities, triggering evacuations of nearly 2,000 people, Indonesia's disaster management agency, BNPB, reported.

About five hours later, Stromboli—a volcano lying within the Tyrrhenian Sea off the north coast of Sicily—began erupting. By 2 p.m. (8 a.m. ET), lava was overflowing from the volcano's northern crater, Italy's National Institute of Geophysics and Volcanology said in a statement. A bigger explosion then began on the central-southern crater,

Videos Show Semeru Volcano Erupt, Spewing Hot Ash As Thousands Flee    Duration 1:02    View on Watch 

This comes a week following the eruption of Mauna Loa on November 27. The Hawaiian volcano is the largest in the world and, until now, has not erupted for nearly 40 years.

The recent eruptions are in no way linked. David Rothery, a professor of planetary geosciences at Britain's Open University, told Newsweek, "They are thousands of kilometers apart, and there is no possible connection between events at one and events at another."

Mount Semeru

Of the three, Mount Semeru is the most deadly volcano, Rothery said. It is 12,060 feet tall and the biggest volcano on the Indonesian island of Java. It is also one of the island's most active volcanoes.

"Semeru is known for large explosive eruptions that can cause large, fast-moving [80 kilometers per hour] and searingly hot pyroclastic flows. This is much the most dangerous volcano of the three, and the Indonesian authorities have wisely been evacuating people from the potential paths of such flows," Rothery said.

"Even after the eruption has ended, ash left by pyroclastic flows and ash that has fallen from the sky is a hazard because it can be remobilized by rainfall and turned into mudflows, known by the Indonesian name of lahars, that can destroy homes and bridges," he said.

Footage taken by the BNPB shows hot pyroclastic flows seeping from Semeru. The video was reposted to Twitter by Paul Byrne, an associate professor of earth and planetary science at Washington University in St. Louis, who called it "terrifying."

Byrne estimated it was moving at around 112 miles per hour. "You can't run from a pyro flow, go ahead and try," he tweeted.

Tamsin Mather, a professor in the Department of Earth Sciences at the University of Oxford, told Newsweek: "This latest paroxysm has not so far been catastrophic, fortunately, but there are reports of over 2,000 people having been evacuated so far. Pyroclastic density currents, a bit like avalanches of hot ash, gas and debris that cascade down from an eruptive vent during an eruption, are a primary hazard.

"Heavy rainfall could also cause lahar—volcanic mudflow—hazards. It is a dynamic situation, and volcanologists on Java are watching things very closely," Mather said.

The Semeru eruption is not unusual, as there were "numerous eruptions in 2021," she said. The "worst eruptive sequence last December displaced more than 4,000 residents and caused around 30 or more fatalities."

Mauna Loa

So far, the other volcano eruptions are not concerning authorities. Lava flows have reached Mauna Loa's Northeast Rift Zone and are a few miles away from the Saddle Road that links two towns Hilo and Kona.

"The rate of lava advance is expected to slow down as it reaches flatter ground," Rothery said. "Lava of this kind is relatively safe if viewed from a distance. The worst-case scenario is that the eruption continues for many months and that the active lava flow front reaches Hilo, but we are a long way from that."

Stromboli

Stromboli is one of the most active volcanoes in the world. It has been erupting almost continuously for the past 90 years, so this latest eruption is no surprise. But the eruption is much larger than usual, Rothery said.

"Stromboli had a larger explosive eruption than its usual very small eruptions that sent a pyroclastic flow into the sea on an uninhabited side of the island," he said.

The volcano last erupted in October, when it spewed lava into the sea.

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about volcanoes? Let us know via science@newsweek.com.

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